Mail*Link(r) SMTP FWD>copper thickness Gary, The primary reason for "thick" copper inner layers is to reduce the electrical resistance of the power/ground plane distribution system. If you go from 70 micrometer [2oz/sq.ft] to 35 micrometer [1 oz/sq.ft.] thick power/ground plane system, you'll double the dc (direct current) voltage drops with the power ground system. Depending on the frequency(ies) of operation, the effect on high frequency analog/digital signals may not be as great. A secondary concern is that some designs use the internal "thick" copper layers for thermal spreaders to minimize the local increase of temperature. Be careful about reducing inner power / ground planes without a good analysis / understanding of the design requirements. Ralph Hersey Lawrence Livermore National Laboratory e-mail: [log in to unmask] -------------------------------------- Date: 4/29/96 6:39 AM From: [log in to unmask] Would like input on the subject of 1 oz. vs. 2 oz copper thickness on inner layers. What types of end products would be affected if 1 oz. were substituted for 2 oz? What design considerations are most critical? Is it safe to say that 1 oz. vs. 2 oz. should no longer be an issue? Thank you for input. Gary Longman Electropac ------------------ RFC822 Header Follows ------------------ Received: by quickmail.llnl.gov with SMTP;29 Apr 1996 06:37:53 -0700 Received: from ipc.org by simon.ipc.org via SMTP (940816.SGI.8.6.9/940406.SGI) id IAA03734; Mon, 29 Apr 1996 08:23:50 -0700 Resent-Date: Mon, 29 Apr 1996 08:23:50 -0700 Received: by ipc.org (Smail3.1.28.1 #2) id m0uDsCE-0000CSC; Mon, 29 Apr 96 07:36 CDT Resent-Sender: [log in to unmask] Old-Return-Path: <[log in to unmask]> From: [log in to unmask] Date: Mon, 29 Apr 1996 08:44:27 -0400 Message-Id: <[log in to unmask]> X-Sender: [log in to unmask] (Unverified) X-Mailer: Windows Eudora Version 1.4.4 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" To: [log in to unmask] Subject: copper thickness Resent-Message-ID: <"7FXaX1.0.3qA.SVBXn"@ipc> Resent-From: [log in to unmask] X-Mailing-List: <[log in to unmask]> archive/latest/3706 X-Loop: [log in to unmask] Precedence: list Resent-Sender: [log in to unmask]